1. Field of the Invention
The present invention relates to a device for controlling the exposure of an electronic camera mounted on an electronic apparatus, such as a portable information terminal.
2. Description of the Related Art
Among electronic apparatuses called portable information terminals, such as notebook personal computers, PDAs (Personal Digital Assistants), and the like, there are some apparatuses which have video cameras and which can photograph the operator of the electronic apparatus or another subject and display the photographed image on a screen of the electronic apparatus. In this kind of electronic apparatus, an image pickup unit of the video camera is generally attached to an upper portion of a display so as to be rotatable in a plane perpendicular to the screen. By rotating the image pickup unit as necessary, the operator or a subject on the opposite side of the apparatus can be photographed. The electronic apparatus also includes a device for controlling the exposure of the video camera which detects the brightness of a photographed image to obtain automatically a proper exposure.
Under normal photographing conditions, the following situations frequently occur: in outdoor photographing, the sky may appear in an upper portion of an image to be photographed, resulting in backlight photographing; and in indoor photographing, a light on a ceiling may exist in an upper portion of a photographed image, resulting in excessive follow light photographing. To realize proper photographing of a natural subject in such a situation, hitherto, a photographed image is divided into an upper area and a lower area and a detection result regarding the brightness of the lower area is highly reflected compared to than that of the upper area to control an exposure.
An operator may train the image pickup unit of the video camera on himself to photograph himself indoors. However, in many cases, a window or light may exist above or near the operator in the background, resulting in backlight photographing or excessive follow light photographing. In such a case, when the method for dividing the photographed image into the upper and lower areas to detect brightness is used, the exposure cannot be properly adjusted so the operator is photographed darkly and an unclear image results.